Note: Descriptions are shown in the official language in which they were submitted.
~ 2~72039
WO 9510~467 PCT/GB9~101978
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INPROV131~TS IN OR BLATING TO ~ICLE ~ ~K~ N~ COLllIQlS
This invention relates to a vehicle steering col~n and in
particular to means to absorb energy transmitted through a
steering column in the event of a vehicle crash and/or driver
impact on a steering wheel.
A known problem has been of how to absorb chest impact
energies of a dri~er in a vehicle which has a rake/reach or
10 tilting steering column. Existing constructions include
cr~Q~ing or exten~;ng a convoluted tube, which have the
problem of relatively high tool cost and low natural
frequency. Other known constructions tend to move the energy
absorbing mechani~m away from the driver and/or involve
15 additional components.
Energy imparted by the driver on the steering wheel in the
event of impact is transmitted from the steering wheel down
the steering col~n. With an adjustable steering col~n, it
20 will be appreciated that the steering coll~ can be moved up
and down and in and out relative to supporting bracketry
remote from the steering wheel and this prevents the use of a
fixed energy absorbing portion between the steering wheel and
supporting brac~etry.
2~
In many steering columns, a steering wheel lock is press
fitted onto the end of an outer tube of the steering column
and in use the steering lock engages with a series of
castalations on the steering wheel to lock it.
As an example, GB-A-2 252 084 discloses a vehicle steering
column with outer and inner col~ members and a steering
column lock. A frangible mounting means is combined with the
W095l08467 PCT/GB94/01978
~ 039 - 2 -
steQring col~ lock for fixing the outer col~ member to the
vehicle body structure, the frangible mounting me~Q allowing
telescopic collapse under axial impact load.
S Reference will be made firstly to Figures 1 to 3 of the
accompanying drawings, in which:-
Figure 1 is a diay o~atic sectional side view of part of a
known form of steering wheel lock housing,
Figure 2 is a diagra=atic underneath ~iew of one end of an
outer tube of a known form of steering column adapted to
receive the steering wheel lock housing of Figure 1, and
Figure 3 is a diay - ~tic side view of the steering column
outer tube of Figure 2 with the steering wheel lock housing of
Figure 1 mounted thereon.
Figure 1 shows part of the known steering wheel lock housing
1, which is basically tubular in form with crush ribs 2
located in its bore. A tapered peg 3 is also pro~ided in the
bore of the steering lock housing 1.
Figure 2 shows the known steering col G outer tube 4 which
has supporting bracketry 5 and a tapered slot 6 at the end of
the steering column adjacent the steering wheel (not shown).
The end lA of the steering wheel lock housing 1 i~ press
fitted onto the end 4A of the steering col~ outer tube 4 80
that the tapered peg 3 locates in the slot 6 and the ribs 2
are crushed by the tube 4. The peg and slot arrangement
transmits torque exerted on the lock housing, during atte~pted
theft, to the steering column bracketry 5.
? 21 1~13~
-- 3
- According to one aspect of the present invention, there i8
provided a vehicle steering column inserted in a tubular body
of a steering wheel lock housing, the tubular body having an
extended bore of a length to accommodate the length of stroke
of collapse of the steering column as required, and the lock
housing and column, in combination, incorporating means to
absorb energy transmitted from the steering wheel in the event
of driver impact on the steering wheel, characterised in that
the steering column is provided with a slot which receives a
protruding peg of ~aid steering wheel lock housing or said
member, the peg being able to slide in said slot in the event
of driver impact on the steering wheel, and the peg being
located normally spaced from the inner end of said slot.
According to another aspect of the present invention, there is
provided a vehicle steering column inserted in a tubular body
of a member fitted on the end of the steering colllm~ on which
a ~teering wheel is mounted, said member being provided with
a tubular body having an extended bore of.a length to
accommodate the length of stroke of collapse of the steering
col~ required and the member and column, in combination,
incorpor~tiilg means to absorb energy transmitted from the
steering ~heel in the event of driver impact on the steering
wheel, characterised in that the steering column is provided
with a slot which receives a protruding peg of said steering
wheel lock housing or said member, the peg being able to slide
in said slot in the event of driver impact on the steering
wheel, and the peg being located normally spaced from the
inner end of said slot.
For a better underst~"~i ng of the invention and to 3how how
the same may be carried into effect, reference will now be
e~EN{~D S~EET
.
2 ! 72~39
- 3a -
made, by way of example, to Figures 4 to 6 of the accompanying
drawings, in which:-
Figure 4 is a view similar to Figure 1 but showing part of a
vehicle steering wheel lock housing according to the
in~ention,
Fiyure 5 is a view similar to Figure 2 but showing one end of
an outer tube of a vehicle steering column according to the
in~ention, and
AMEN~ED S~E~
W095/08467 PCT/GB94/01978
39 4 -
Figure 6 i8 a ~iew of the outer tube of Figure 5 with the
steering lock housing of Figure 4 mounted thereon.
Re~erring to Figure 4, the present vehicle steering wheel lock
S housing 10 has a tubular body which is pro~ided with an
extended bore as compared with known steering wheel lock
housings, the bore being extended to accn~ oA~te the length of
stroke of collapse of the steering wheel required. The bore
is slightly tapered. As with the known type o vehicle
steering wheel lock housing, internal `crush ribs 20 are
provided, which are also gi~en a slight taper as is a short,
inter~al peg 30. The area indicated by reference lOB is also
relieved to allow for ~ool removal during manufacture, since
the lock housing can be moulded or die cast.
As seen in Figure 5, the present vehicle steering column has
an extended outer tube 40, again with supporting bracketry 50,
the end 40A of the outer tube 40 being pro~ided with an
extended slot 60, of parallel section to allow the tube 40 to
slide fully into the lock housing 10. Again, it is the end
lOA of the lock housing into which the outer tube 40 is
introduced.
As with the known form, as the tube 40 is inserted in the lock
housing 10, the internal ribs 20 are crushed and the tapered
bore 20 and peg 30 cause the lock housing 10 to come into
interference fit with the outside of the tube 40. The load on
the interference fit can be easily adjusted or tuned by
modifying the bore and peg form and/or taper relationship with
the outside of the tube 40. A typical load of the lock
housing 10 as pushed onto the tube 40 in its normal position
is approximately 2-5 Kn.
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2 1 72Q3q
Wo95/08467 PCTIGB94/01978
- 5 -
When located in its normal position, the peg 30 will still lie
some distance ~rom the inner end of the slot 60.
In the event of a vehicle crash, for example, the lock hou~ing
10 is dri~en further down the slot 60, cont;n~;n~ to be loaded
at the 2-5 Rn level (dep~nA;ng on the type of vehicle) until
r~Ac~;ng the end of its travel. ~y limiting the length of the
peg 30, a substantially constant load can be achieved, as once
the tube has passed about the peg, the tube 40 will close in
around the slot 60. The expectations of collapse, i.e. the
shape of the designed collapse curve, can, however, be
modified to suit individual applications depenA;ng on peg
length and/or angle, bore rib taper and form, tube dia_eter
and taper, etc.
The t~nA~ncy on collapse is for the tube 40 not to remain
circular when pressed into the lock housing 10 but rather it
becomes ellipsoid in the region of the ribs 20 and the main
bore of the lock housing 10.
It will be appreciated that the present steering column and
lock in co_bination provides an energy absorbing mechanism
which utilises existing components, with minor A~AeA material
cost a3 comr~ed with known constructions, which makes it
suitable for use on all types of steering column.
The lock housing and/or tube combination can be made of steel,
plastics material or any other suitable material.
In order further to control the collapse curve, additional
energy absorbing mechanisms can be incorporated in the
combination, for example, balls or spring clips.
W095/08467 PCT/GB94/01978
3q
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It will be appreciated that, instead of the ~teering wheel
lock housing, another member could be mounted on the end of
the steering col-~mn and be constructed in the ~ame or 3imilar
manner to achie~e the required collapse facility according to
the in~ention. For example, the m~her could be a bearing
carrier for the adjacent steering wheel and/or inner steering
col~ shaft.
For clarity, the actual lock mech~n;sm associated with the
lock housing lO has not been shown in the drawings.
